Risk Management Solutions (www.rms.com) announced the launch of new earthquake models for the western U.S. and western Canada. The models use the latest data on seismic risk from the U.S. Geological Survey (USGS) 2002 National Seismic Hazard Maps, and include a major innovation in the use of spectral response for the measurement of earthquake shaking and the calculation of damage at a site.
The models were introduced to over 400 insurance and reinsurance industry representatives at the RMS Client Conference this week in Carlsbad, California. In a series of lectures, Q&A sessions, and case studies, RMS engineers provided details on the underlying research for the models. There was also a keynote presentation on recent developments in earthquake hazard research by Dr. Lucy Jones, scientist-in-charge of the USGS earthquake activities for southern California.
Earthquake source characteristics in the RMS model incorporate the latest hazard components of the 2002 USGS National Seismic Hazard Maps. These include the location, maximum magnitude, and recurrence interval for active faults. The three-dimensional character of faults is modeled for better representation of risk from the many thrust faults in the Los Angeles area, and from subduction and intraslab sources in the Pacific Northwest and British Columbia. Time dependence on major faults has also been updated to reflect the most recent geological research, and the model accounts for the possibility of “cascade” earthquakes, where rupture jumps from one fault to another causing a larger magnitude event.
At the heart of the RMS model is a new spectral response analytical engine that takes the full complexity of earthquake vibration from the source, through the ground, and into the building structure. The engine fully captures the interdependencies of earthquake magnitude, style of faulting, distance and attenuation, underlying soil characteristics, building height, and construction material. The methodology for building performance assessment is based on research from the Pacific Earthquake Engineering Research Center (PEER), calibrated by RMS engineers using detailed insurance loss data from past earthquakes.
One of the key components of the spectral response analysis is a greatly expanded database of soil characteristics that define how specific earthquake ground motions are transformed as they reach the foundations of a building. The expanded data cover more than 20 metropolitan areas of the western U.S. and Canada at a resolution of 100 meters or better. Outside of these metro areas, RMS has developed a proprietary geographic indexing system known as the Variable Resolution Grid (VRG) to store data at a resolution finer than ZIP Code.
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